Omaru Polka (尾丸ポルカ) is a member of the 5th generation of Hololive talents, and debuted on August 16, 2020. She is a quarter-part fennec circus-less ring mistress who decided to turn Hololive into her circus.
She streams talk streams, singing/karaoke streams and sometimes game streams, even if by her own admission she is not very good at them. She tried keeping a stream schedule at first, but eventually gave up: dubbing herself a "guerrilla queen", she now schedules her own streams from anywhere between 15 minutes to 2 hours in advance with next to no prior warning, and at unpredictable times ranging from early in the morning to very late at night.
Because of her circus theming, Polka's representative mark is a circus tent (🎪). A bell (🔔) is also associated with Polka by her fans because of her prolific use of it in streams.
Polka is highly energetic, and often speaks faster than even native Japanese viewers are capable of understanding. Her emotions fluctuate wildly: one moment she is extremely loud and energetic, and the next she is quiet and subdued.
Polka's streams are chaotic: she talks fast and loose, jumping quickly to and from a variety of topics. Even if she has a list of talking points, she quickly veers into related tangents, only returning to the original topic after a long time. Her unpredictability extends to how she plays games; this is more noticeable in open world games, like Minecraft and ARK, where she plays with a plan in mind which eventually gets abandoned in favor of doing something else entirely that catches her attention on the spot. Her in-game projects are often stalled by these distractions despite her intention to work hard on them, though when she does complete one it is after numerous adventurous detours.
By her own account, Polka is easily affected by the weather, in particular atmospheric pressure. If she decides to stream on a day with low pressure, she almost always starts with less energy than usual; eventually she perks back up as she has fun doing whatever activity she is streaming. On more than one occasion she has streamed 2+ hours of karaoke early in the morning simply because she had a headache and thought to get rid of it by singing.
Like Marine, Polka is knowledgeable about 90s and 2000s anime and otaku culture, and is touchy about her age.
Starting on April 29, 2021, Polka started releasing 10-12 minute weekly videos dubbed Legend of Polka (ポルカの伝説). In each video, the Hololive staff member Ms. Izutsu (井筒さん) brings a new situation for Polka to react and respond to, such as manga Polka made in her childhood, or kids asking Polka for advice in various topics.
A playlist of all the Legend of Polka episodes can be found here.
Starting September 14th, 2021, Polka began releasing a weekly project called Polka Radio Ka (ポルカラジオカ). This is a "short radio" project, with each audio-only video lasting around 10 minutes and focusing on 1 to 3 topics. This radio show is designed to be a more relaxed and personal project, in contrast with Polka's more energetic streams, and the more involved production of Legend of Polka.
Please do not have conversations in the pre-stream chat! (※ Don't have private conversations, they change the atmosphere)
Please do not talk too much about unrelated topics during the stream!
Please do not talk about other vtubers unless I bring them up!
Likewise, please do not bring me up in other streams!
The atmosphere of Polka's stream should be enjoyed in here only.
Please be careful about excessive spoilers. Please be considerate of others and go with the flow (of the stream).
Please don't be overzealous about enforcing the rules. Getting along with others is the number one priority!
Please refrain from getting into arguments in chat; that is not what Polka wishes for in a stream. If you see something you don't agree with, blocking the sender is an option. The best response is to not engage.
Polka's fans are collectively called "Omaru-za" (おまる座, "The Omaru Troupe"). Individual fans are called "Zain" (座員, "Troupe members"). They are represented by a small fennec-like mascot from a fan-made Zain dress-up maker that was ultimately adopted and made official by Polka herself.
Ninomae Ina'nis goes to the hololive Japan Minecraft server, on a date with Polka and Nene. But Polka and Nene are more interested in flirting with Ina and foiling each other's advances, than in showing her guest around.
ENDLESS BLUE CLAPPER #気圧敗北部 【尾丸ポルカ/ホロライブ】
Stream Date: Jan 14, 2021
Polka sings BLUE CLAPPER. Only BLUE CLAPPER. For two hours. Exactly 30 times.
Stream Date: Jan 26, 2021
Early morning talk stream, on a day with really bad atmospheric pressure, with an extremely sleepy Polka.
【Duolingo】POLKA-chan Let's study ENG! 【尾丸ポルカ/ホロライブ】
Stream Date: Mar 13, 2021
Polka studies English using Duolingo. You'd think the language itself would be confusing, but in reality it's Duolingo's characters and phrase choice that confuse Polka. What's up with that bear? And who is Hinata?
Stream Date: Mar 15, 2021
Polka answers questions on Marshmallow. Or at least that was the intention -- instead, she received many multi-question stories and fanfics. What does Polka do? Read them dramatically, of course!
Stream Date: Aug 11, 2021
Polka recording an official version of the Shiranui Construction Anthem based on a fan submission. SHI! RA! NUI! KENSETSU!
Has a notoriously poor sense of direction in games. Coupled with her curious and unpredictable nature, her gaming streams are equal parts getting lost and getting back again.
One of her streaming quirks is the ending fade-out: as her stream ending sequence plays, she frequently keeps talking over it, her voice volume fading out gradually.
When Polka reads Superchats, she plays the Superchat Song that a fan made for her. It is customary during this time that her fans copy and paste a brief reading of the lyrics of the song: ｽｰﾊﾟｰﾁｬｯﾄｱﾘｶﾞﾄｰ🎶ｽｰﾊﾟｰﾁｬｯﾄﾀﾞﾖｰ🎶ｽｰﾊﾟｰﾁｬｯﾄｱﾘｶﾞﾄｰ🎶ﾄｯﾃﾓｳﾚｼｲﾖｰ🎶
Even if she cannot speak English, Polka frequently tries to engage with her foreign fans:
At the start of most streams, after her greeting in Japanese, she always greets everyone in the world in English: "Good morning, good evening, good afternoon!"
She has played Among Us, in English, with fans around the world. 
Polka has talked frequently about her interactions with her "very cute" manager, Mane-chan (マネちゃん).
During her childhood, Polka joined the girl scouts because she thought the uniform was cute.
Polka's mom watches her daughter's streams.
She is part of Polka's YouTube membership, and pays close attention to what the viewers are commenting about her daughter.
Eventually she was featured in an episode of Legend of Polka, in which Polka checks in with her mom on on a phone call.
At some point between November and December 2020, after Polka's first Ring Fit Adventure stream, her mom took Polka's Ring-con and game and started playing herself. By the time the episode of Legend of Polka that features her was filmed, she was Level 175 in the game.
Polka suffers from frequent headaches whenever there is low atmospheric pressure. She has struggled with these her entire life, and frequently takes pain-relievers as a result.
Polka is afraid of dentists:
When she was young, a botched dental operation caused her to develop a blister/growth in her upper jaw, causing a slight speech impediment: her pronounciation of the "nya, nyi, nyu, nye, nyo" sounds are more like ni-tya, ni-tyi, ni-tyu, ni-tye, ni-tyo. It is possible to remove said growth, but as it would be very painful, would require anesthesia, and there is no guarantee it will not come back, combined with her fear of dentists, Polka just decided to live with it.
Polka started having tooth pains in 2021. Mid-May, she decided to go to the dentist, but not before having a nearly 2-hour-long karaoke stream to give herself courage.  This eventually led to her making regular visits to the dentist, until she completed her treatment at the end of July.
Polka works very hard behind the scenes in many projects, and not just for herself: for example, she was involved in designing the merchandise for the Bloom, concert, and was the one who came up with the idea of the metallic floral charms instead of the more common acrylic keychains.
Polka a playlist called 🔴NOW on her channel. By the description, she intends to complete the games/projects she has added to this playlist.
While other members read Superchat donations at the end of streams or on semi-regularly scheduled streams, Polka can go for weeks and even months without a single Superchat reading stream. Instead of letting months of donations accumulate, Polka found solution: adding the names of Superchat donors as credits in Legend of Polka (Including, of course, the Superchat song).
Shares the same Illustrator with the following VTubers:
Is one of the Hololive Production VTubers with a verified YouTube channel. Other verified members can be found here.
Disgaea 6: On February 24, 2021, Nippon Ichi Software released a trailer announcing that 5 Hololive members would be included in Disgaea 6 as a free Downloadable Content. These characters are also available in the Worldwide/English version of the game since its launch on June 29, 2021.
Polka's character is PolPol, a Mage with a Polka-inspired skin and the unique class Pirika Circus CEO.
Family Mart: On May 6, 2021, the Japanese convenience store Family Mart announced the third edition of its "Holomart" (ホロマート) collaboration with hololive, with the title Holomart Campaign vol.3 5th Generation's "May" you be happy (ホロマート キャンペーンvol.3 5月5期生『May』you be happy). This collaboration included clear file folders featuring the members of Hololive's 5th Generation: Shishiro Botan, Yukihana Lamy, Omaru Polka and Momosuzu Nene.
Village Vanguard: On June 26, 2021, the official account for the bookstore Village Vanguard announced a collaboration with the members of Hololive 5th Generation. This limited-time collaboration ran from July 2 to July 18th, 2021, and is themed around Animal Ears Café (けもみみカフェ) with various goods and apparel featuring Shishiro Botan, Yukihana Lamy (with cat ears), Omaru Polka and Momosuzu Nene (with bear ears) in café maid outfits.
Fuji-Q Highland: On September 6, 2021, Hololive and the theme park Fuji-Q Highland announced a first collaboration called "hololive" in Fuji-Q Highland (「ホロライブ」in 富士急ハイランド) that would run from September 18 to October 31, 2021.
The collaboration includes: special event tickets, Hololive talents making ride and attraction announcements, decorations in the main entrance, stamp and attraction rallies, various collaboration foods and merchandise.
Little Witch Nobeta: On October 1, 2021, Pupuya games, the developers of the action adventure game Little Witch Nobeta announced that three hololive talents would be voicing characters in the game: Omaru Polka as Ribbon Loving Soul Doll – Tania; Shirakami Fubuki as Doll Hugging Soul Doll – Monica; and Shirogane Noel as Soul Doll of The Throne – Vanessa.
Polka and her chat tend to use the syllable POL (ぽる) and substitute/add it in other words. Some examples include:
OHAPOL: Polka's "Good morning" greeting in Twitter.
HIRUPOL: Another greeting, when her first Twitter post of the day occurs around noon.
OYAPOL: Good night greeting, said by Polka on Twitter when she goes to sleep.
POLTATO PC: Used to describe the old computer Polka was using when she started streaming.
ぽ: In the song Po, Polka is unable to speak properly and replaces all syllables in her speech with Po. Since the song was released, Polka, other Hololive members, and the fans alike have written tweets and talked in "Po-speech".
After her first anniversary, Polka changed her Twitter profile from "尾丸ポルカ🎪ホロライブ5期生" to "尾丸ポルカ🎪ぽロライブぽ期生". She reverted it back after a couple of weeks.
For her 2021 Birthday, she received the following instruments as presents from the fans: Tamayurarin Buddhist Bell, Pachi Pachi Clappy, Red-Blue Clapper/Hand Rattle, Kazoo, Alto Recorder, Street Drum, Vuvuzela, Tongue Drum, Accordion. 
↑The English rules here are different to the ones in Polka's stream descriptions. This is an English translation of her original Japanese rules, kindly contributed by the users of the Hologram Circus Discord fan server